docs: def set_backlight(self, backlight):
          """Enable or disable the backlight.  If PWM is not enabled (default), a
          non-zero backlight value will turn on the backlight and a zero value will
          turn it off.  If PWM is enabled, backlight can be any value from 0.0 to
          1.0, with 1.0 being full intensity backlight.
          """
          if self._backlight is not None:
              if self._pwm_enabled:
                  self._pwm.set_duty_cycle(self._backlight, self._pwm_duty_cycle(backlight))
              else:
                  self._gpio.output(self._backlight, self._blpol if backlight else not self._blpol)